The present invention relates to an apparatus for filling caulking tubes and more particularly the present invention relates to an apparatus for filling caulking tubes with one-component room temperature vulcanizable silicone rubber compositions.
Caulking tubes are well known. Such caulking tubes or cartridges are usually filled with compositions which it is desired to prevent being exposed to atmospheric moisture or the elements prior to cure. When it is desired to use the material in the caulking cartridge, the tip of the nozzle of the caulking cartridge is cut and the caulking cartridge is put in a caulking gun whereupon a piston applies pressure to the plunger at the rear end of the caulking tube and forces the material out of the caulking tube.
The means for filling such caulking tube is an art in itself. In the past there have been developed machines for filling caulking tubes or other packages with a low viscosity material, automatically. Such machines would fill the caulking cartridges or other packages with a low viscosity material. Generally, such an apparatus comprises a drive means which drives a conveyor belt at the lower portion of the machine. The conveyor belt means contained receptacle means for positioning and maintaining in a vertical position for 1 thru 6 empty caulking tubes. There was reservoir means in the upper portion of the frame of the machine in which there was present the composition that was desired to be packaged. From the drive means there was linkage means, and what shall be referred to as "valve means" which generally comprises a cylindrical shaft which was present and revolved in a rectangular block and which cylindrical block had cut-out cavities. There was also affixed to such cylindrical shaft means, piston and cylinder means. Accordingly, the drive means would drive the linkage means which would drive the piston means to create a suction in the piston and cylinder means so as to force by gravity feed as well as suction the composition from the reservoir means into the cavities in the cylindrical shaft means as well as the spaces that were present in the piston and cylinder means. Then by the valve core means being turned in a downward direction by the linkage means and by the pistons being actuated to force the composition out of the cylinder and piston means, the composition would be forced out of the cylinder and piston means and out of the core means through passage tubes and into the empty caulking cartridges as the empty caulking cartridges presented themselves in time synchronization beneath the pallet means and the block means at the proper moment. This would be done such that all the caulking tubes under fill tubes would be filled with the composition at one time. Then the conveyor means would carry the cartridges further where the caulker caps would be inserted in the rear end of the caulking tubes so as to seal the composition that was in the caulking tubes.
It should be noted that the cavities in the core means which was present within the block means, as well as in the cylinder and piston means, was such that only the desired quantity of material was deposited in such cavities during the suction action of the cylinder and piston means such that when the piston of the piston and cylinder means forced the composition out from said cylinder and piston means through said core means and block means into the caulking cartridges only the desired quantity of material was deposited in the empty caulking tubes. Such apparatuses were advantageous for filling non-viscous compositions. They had certain disadvantages with respect to viscous compositions. Thus, with viscous compositions such as room temperature vulcanizable silicone rubber compositions which may have a viscosity in the uncured form of anywhere from 50,000 centipoise to 1,000,000 centipoise at 25.degree. C., difficulty was encountered. For instance, in the prior art machine the shaft or core means would be composed of carbon steel while the block means was composed of cast iron, and the steel shaft would rotate in the bore present in the cast iron block with only teflon ring means at the extreme ends of the block and shaft means sealing the two operating members. However, viscous silicone compositions such as, one-component room temperature vulcanizable silicone rubber compositions mentioned above are very hard on the surface of such steel core and cast iron block means and would result in the cast iron being worn away all too rapidly. Brass was attempted to be utilized for a core means. However, even that wore away too quickly and also had a tendency to turn the silicone composition green. Accordingly, it was decided to utilize a carbon steel or stainless steel core, that is, a cylindrical shaft means and stainless steel or cast iron block in which the core rotated. However, even though such stainless steel or carbon steel did not affect the color of the silicone compositions or other compositions that might be put through such an apparatus, nevertheless, there was difficulty in that rapid metal-to-metal wear would result in the core means.
This would cause the core means to grow smaller or the block to enlarge in size or egg-shaped in cross-section and result in silicone composition or other type of composition being packaged leaking from the machine and being deposited on the caulking cartridges such that it resulted in dirty caulking cartridges which may have to be rejected.
In another respect, it was disadvantageous since it is desired to keep such one-component room temperature vulcanizable silicone rubber compositions free from atmospheric moisture; otherwise, the composition will cure to an elastomer. Accordingly, with the wearing away of such core means, air would leak into and get forced into the uncured silicone composition and would result in the composition prematurely curing in the apparatus or in the caulking tube which was extremely undesirable. Accordingly, it was highly desirable to find a modification or improvement in such core means and block means in such caulking tube apparatus filling machinery such that the apparatus could be filled without prematurely curing the silicone composition.
In addition, it should be noted in order to repair such apparatuses after the core means have been ground to a smaller shape or egg-shaped from the undue wear or metal-to-metal wear between the core means and the block means, it was necessary to regrind the block means so that the bore passing through it was circular in cross-section and to obtain a new core means which would be of the appropriate size in the enlarged bore of the block means. This, as can be appreciated, was an unduly expensive repair procedure to follow. Also, this repair procedure was expensive in that the down time for the machine kept the apparatus from working on the assembly line to fill the necessary amount of cartridge tubes.
Accordingly, it was highly desirable to find a means for substantially reducing the wear between the core means and the block means for such caulking tube filling machinery for viscous, abrasive materials. In the past, also, such machines had been made for the filling of four empty caulking cartridges at a time. Accordingly, it was highly desirable to increase such filling capacity to 6 empty cartridges at a time so as to increase the production that was possible from the packaging operation with the same number of operators.
One difficulty for making a machine capable of filling 6 cartridges at a time was that it was not possible to make a precision block with a bore long enough to accommodate the filling of 6 cartridges to package these silicone materials, which under heat and pressure revert to abrasive silica and which as the result of the core and housing rubbing in contact is followed by deformation of the core because of its length to accommodate 6 caulkers. Accordingly, this was a problem in the prior caulking tube filling apparatuses.
Accordingly, it is one object of the present invention to provide for an apparatus for filling caulking tubes in which there is substantially reduced wear between the core means and the block means in said apparatus.
It is another object of the present invention to provide for an apparatus for filling caulking tubes which can fill 6 caulking tubes at one time under heavy pressures such as required for packaging silicone compounds which can be 8,000 lbs. per piston or 24 tons for a six-line machine.
It is an additional object of the present invention to provide for an apparatus for filling caulking tubes in which the valve core or shaft means through which the composition passes which is to be placed in the caulking tubes, that said shaft rotates in a valve block supported by means of sealed roller bearings.
It is yet an additional object of the present invention to provide an apparatus for filling caulking tubes with a viscous silicone composition in which there is substantial less wearing between the core means and the block means through which the viscous composition passes before it passes into the caulking tubes.
These and other objects of the present invention are accomplished by means of the invention shown in the Figures below.